Manufacture of resilient springs



Nov. 22, 1938. R. c. PIERCE 2,137,698

MANUFACTURE OF RESILIENT SPRINGS Filed April 17, I1936 2 Sheets-Shed l P05597' 6 /D/EFPCE BY l ATTORNEYS.

Nov. 22, 1938, RQ c. PIERCE MANUFACTURE OF RESILIENT SPRINGS Filed April 17, A1956 2 Sheets-Shea?I 2 6 4,2 4 m 4 0 K o .0 Z 4 J 4. e b Q Q Lr x4 G M 0 O w e e 4 \\\\\\|l/ AM k G G /CPOBERTCP/E/Qc BY CMA? 506% le l TTORNEYJ.

Patented Nov. 22, 1938 UNITED STATES MANUFACTURE F RESILIENT SPRINGS Robert C. Pierce, Niles, Mich., assignor to National Standard Company, Niles, Mich., a corporation of Michigan Application April 17, 1936, Serial `No. 74,844

11 Claims.

This invention relates to resilient springs and their manufacture, and is illustrated in connection with the manufacture of a resilient spring from an open-mesh braid of steel Wire.

The novel spring, manufactured as herein described, consists of an open-mesh braid of steel -wires passing alternately over and under each other diagonally across the braid and formed with spring reverse bends at the edges of the braid, the resilience of the entire spring being the sum total of the resilience of all of these bends. Preferably the braid is made of highcarbon (e. g. .65% or above) cold-drawn steel wire, although very good results can also be obtained by using wire above .45% or .59% carbon and heating it and quenching in oil, to temper it, after the spreading operation described below.

Preferably the material used is standard wire braid, and the open-mesh construction is in that case secured by running the braid through a novel machine having means, such as two sets of differentially driven rolls, for spreading the braid widthwise. The faster-driven rolls engage the braid rst, and cause it to spread widthwise in shortening itself sufficiently to pass between the slower rolls. Means, such as spaced parallel plates between which the braid passes from the faster to the slower rolls, prevents buckling during the spreading operation. p

For some purposes it is desirable to have the spring in relatively short sections, with the ends of the sections in the compact form of the original unspread braid. To this end, the machine may be provided with means for periodically spreading the second set of rolls apart, thereby interrupting the spreading action. This leaves unspread portions, through which the braid is afterwards cut. l l

The second set of rolls is under heavy spring pressure, to compress beyond the elastic limit of the steel the bends in the wire at the edges of the braid, to set them permanently and thereby transform them into a series of little separate springs acting cumulatively. vIf the pressure is to be heavy enough to make it desirable, the second set of rolls may either be made with the surface of one sufciently yieldable to insure pressure directly on the bends in the wire, or one roll may have the part engaging the body of the braid slightly smaller in diameter than the parts acting on the edges of the braid.

The above and other objects and features of the invention, including various novel constructions and desirable particular arrangements, will be apparent from the following description of the illustrative constructions shown in the accompanying drawings, in which:

Figure l is a side elevation of a braid-spreading machine, partly broken away to show parts which would otherwise be hidden;

Figure 2 is a top plan View thereof;

Figure 3 is a perspective view of a similar machine provided With means for periodically interrupting the spreading action;

Figure 4 is a section on the line 4-4 of Figure 3, showing the guide plates preventing buckling of the braid;

Figure 5 is an exaggerated plan View of the braid as it passes through the machine;

Figure 6 is a diagram showing the braid of Figure 5 in side elevation, withthe positions of the rolls indicated;

Figure 'l is an elevation showing the braid-engaging parts of the second set of rolls when sufcient pressure is to be applied to necessitate larger roll diameters at the edges of the braid than across the body of the braid;

Figure 8, 9, and 10 are sections showing before compression, from different points of view, one of the reverse bends of the wire at one edge of the braid; and f Figures 11, 12, and 13 are similar views showing the bend after compression. Y

The material which I prefer to use, in the manner described below, is a at braid I0 of wires Ywhich pass alternately over and under each other diagonally across the braid, with reverse bends at the edges, all of the wires extending for the full length of the braid. Preferably the wires are of cold-drawn high carbon steel, for example .65% carbon steel, which can be set in the desired spring formation by compressing the bends at the edges of the spread braid beyond the elastic limit of the steel, without further treatment of the steel.

However, good results can also be obtained by using a steel of .45% or .50% (or higher) carbon, and tempering it after it leaves the spreading machine, by heating it and then quenching in oil.

The braid is fed between a rst or feeding pair of rolls I2 and I4, then between parallel spaced guide plates I6 which guard against buckling, and then between a second or pressure set of rolls I8 and 20 which are driven more slowly than the rolls I2 and I4. The rolls I2 and I4 are drivably interconnected by gears 22, and the rolls I8 and 20 by gears 24.

' The rst set of rolls is driven by means such as a sprocket chain 26 passing over a sprocket 28 on the end of one of the rolls, and the second set is driven by a sprocket chain 30 passing over a sprocket 32 on the end of one of those rolls. The sprocket chains 26 and 30 are driven in any desired manner, preferably by means operated by an electric motor (not shown).

Where it is desired periodicallyy to interrupt the spreading action, the modification of Figure 3 may be used. In this figure all parts corresponding to parts in Figure 1 are indicated by the same reference characters increased by 100.

In this modified machine, the rolls H8 and |20 are normally urged together by heavy springs 40 acting on pivoted levers 412 carrying the roll Il8. Periodically a cam 44, driven by suitable gearing 46 interconnected to be driven synchronously with the gearing for the rolls l2-I4-I8-20, rocks a lever 48 on a shaft 50 having xed thereon arms connected by links 52 to the levers 42. This rocks the roll H8 periodically away from roll |20, to have unspread sections 54, through which the braid is afterwards cut.

As shown on an exaggerated scale in Figures 5 and 6, the braid is spread widthwise slightly wider than its final width, and heavily compressed while held so spread. As illustrated in Figures 8-10 showing a reverse bend at one edge of the braid before compression, and Figures 11-13 showing the same after compression, these bends are compressed beyond the elastic limit of the steel, and form a series of little wire springs whose cumulative total forms the entire spring. After leaving Ihe rolls I8-2ll, the braid contracts slightly widthwise, as exaggerated in Figure 5, to its final width.

If desired, one or both of the rolls |8-2 may be faced with material, such as vulcanized rubber, which will yield sufficiently where the braid wires cross each other to insure that the edge wires are adequately compressed.

Or, if preferred, one or both rolls may be of two diameters, as shown for rolls 2 |8-220 in Figure 7, so that for the body of the braid they are spaced apart a distance equal to the diameter of two wires While at the edges they are spaced apart a distance equal to the diameter of a single Wire.

Finally, if cold drawn spring wire has not been used, the braid is tempered by heating and quenching in oil.

An expanded braid spring as described above may be used to form slats for Venetian blinds and is particularly useful in the manufacture of furniture to form a support for the vseats of chairs and the like. It is also adapted for use in a great many other places where a certain amount of elasticity in tension is desirable.

While illustrative machines have been described in detail, it is not my intention toI limit the scope of the invention by that description, or otherwise than by the terms of the appended claims. This application is in part a continuation of my application No. 41,199, led September 19, 1935.

The article and method disclosed herein are claimed in application No. 232,265, filed Sept. 29, 1938.

I claim:

l. Apparatus for use in making Venetian blinds or the like comprising means for feeding a braid of wires each of which extends continuously from one end of the braid to theA other and which passes alternately over and under each other and which are formed in reverse bends at the edges of the braid, and means for spreading the wires of the braid fed thereby to form relatively large spaces between them and means to'give a permanent set to said bends when the Wires are spread whereby the wires will remain spread.

2. Apparatus of the class described comprising a pair of driven rollers for feeding a at braid of Wires each of which extends continuously from one end of the braid to the other and which passes alternately over and under each other and which are formed in reverse bends at the edges of the braid, a pair of rollers driven more slowly than the rst rollers and spaced therefrom and between which the braid passes, and parallel plates on opposite sides of the braid between the two pairs of rollers preventing crosswise buckling of the braid and insuring that the difference in speed of the two pairs of rollers will cause widthwise expansion of the braid, said second named rollers being constructed and arranged to give a permanent set to said bends when the braid is expanded widthwise.

3. Apparatus of the class described comprising means for progressively spreading widthwise a wire braid, and means for periodically interrupting the spreading action of the spreading means.

4. Apparatus of the class described comprising differentially-driven sets of rolls for progressively spreading widthwise a Wire braid, and means for periodically separating the rolls of one set to interrupt the spreading action of said rolls.

5. Apparatus of the class described comprising differentially-driven sets of rolls for progressively spreading widthwise a wire braid, means between said sets for preventing buckling of the braid, and means for periodically separating the rolls of one set to interrupt the spreading action of said rolls.

6. Apparatus of the class described comprising differentially-driven sets of rolls for progressively spreading widthwise a wire braid, parallel spaced guide plates between said sets for preventing buckling of the braid, and means Vfor periodically separating the rolls of one set to interrupt the spreading action of said rolls.

7. Apparatus of the class described comprising differentially-driven sets of rolls of which the Yfirst set is driven faster than the second and which -with suicient pressure to give it a permanent set.

8. Apparatus of the class described comprising differentially-driven sets of rolls of which lthe first set is driven faster than the second and which are constructed and arranged to spread widthwise a wire braid the rollers of the second set being spaced apart asmaller distance adjacent their edges than at their center portion to engage a single thickness of wire at the edges of the braid with sufficient pressure to give it a permanent set, and means between said sets for preventing buckling of the braid.

9. Apparatus of the class described comprising diierentially-driven sets of rolls of which the first set is driven faster than the second and which are constructed and arranged to spread widthwise a wire braid consisting of wires each extending diagonally back and forth across the braid and over and under the other wires and having at the edges of the braid bends which are inclined to the plane of the braid., the first set of rolls gripping the braid sufficiently to force it to spread widthwise as the slower second set of rolls holds the braid back but which do not substantially affect said bends inv the wires at the edges of the braid, in combination with means for applying suiiicient pressure to the rolls of the second set to set said bends in the Wire at the edges of the spread braid so that the spread braid forms a resilient spring.

1G. Apparatus of the class described comprising means for forming an open-mesh braid of wires each of which extends continuously from one end of the braid to the other and which pass alternately over and under each other and which are formed in reverse bends at the edges of the braid and which are formed with relatively large open spaces between the wires, and means for compressing said braid heavily enough permanently to set said bends and form a resilient spring of said braid.

11. Apparatus of the class described comprising means for forming an open-mesh braid oi wires each of which extends continuously from one end of the braid to the other and which pass alternately over and under each other and which are formed in reverse bends at the edges of the braid and which are formed with relatively large open spaces between the wires, and means .for compressing said braid heavily enough permanently to set said bends and form a resilient spring of said braid, said compressing means including rolls spaced apart a distance equal to the diameters of two wires throughout most of the Width of the braid, and spaced apart a distance equal to the diameter of a single wire at the edges of the braid.

ROBERT C. PIERCE. 

